KR102513518B1 - Olefin polymerization method using antistatic agent for metallocene olefin polymerization process - Google Patents

Abstract

Discontinuity events due to sheeting or drooling phenomena generated in the olefin polymerization process are effectively reduced, enabling long-term continuous operation, and the obtained final product is suitable for various applications including food contact applications. An antistatic agent for a metallocene olefin polymerization process that can be applied and a polymerization method using the same are disclosed. Forming a mixture in which an antistatic agent including diglycerol oleate is mixed with the low molecular hydrocarbon, a metallocene-based catalyst composition comprising the antistatic agent mixture, a metallocene catalyst, and an aluminoxane in 2 and feeding one or more polymerization reactors and polymerizing one or more alpha-olefins in the presence of the antistatic agent mixture and the catalyst composition.

Description

Olefin polymerization method using antistatic agent for metallocene olefin polymerization process}

The present invention relates to an olefin polymerization method using an antistatic agent for a metallocene olefin polymerization process, and more particularly, to a discontinuity event due to sheeting or drooling phenomenon occurring in an olefin polymerization process This effectively reduces long-term continuous operation, and the obtained final product relates to an olefin polymerization method using an antistatic agent for a metallocene olefin polymerization process that can be applied to various applications including food contact applications.

Polyolefins produced using metallocene catalysts are characterized by narrow molecular weight distributions and narrow chemical compositions, providing products with improved structural performance, such as high impact strength and transparency in films.

In spite of these advantages of metallocene catalysts, "sheeting" or "drooling" may occur when metallocene catalysts are used in conventional polymerization systems, particularly in fluidized bed reactors. See US Patent Nos. 5,436,304 and 5,405,922. Sheeting is the adhesion of fused catalyst and resin particles to the reactor wall. Drooling (or "dome sheet", Drooling) is the same as sheeting in that it is the adhesion of fused catalyst and resin particles to the reactor wall, except that it occurs in the conical part of the dome or hemispherical head on the top of the reactor. Sheeting can be a problem in commercial gas phase polyolefin production reactors if not adequately mitigated. The problem is characterized by the formation of large solid masses of polymer on the walls of the reactor. These solid masses or polymers (sheets) eventually dislodge from the walls and fall into the reaction zone, where they interfere with fluidization, block the product outlet, and eventually cause a situation that forces the reactor to shut down.

Accordingly, various seating control methods have been developed. This often involves monitoring the static charge near the walls of the reactor in areas where sheeting is known to form, and introducing a static control agent into the reactor if the static level is outside a certain range. For example, U.S. Pat. Nos. 4,803,251 and 5,391,657 disclose the use of various chemical additives in a fluidized bed reactor to control static charge in the reactor. US Patent Nos. 4,803,251 and 5,391,657 disclose that static electricity plays an important role in sheeting processes using Ziegler-Natta catalysts. When the level of static charge on the catalyst and resin particles exceeds a certain critical level, the particles adhere to the grounded metal walls of the reactor by electrostatic forces. If allowed to exist on the wall long enough under a reactive environment, excessive temperatures can lead to particle sintering and melting, creating sheets or drules.

U.S. Patent No. 4,532,311 discloses the use of a reactor electrostatic probe (voltage probe) to obtain an indication of the electrical conductivity of the fluidized bed. U.S. Patent No. 4,855,370 controls the level of static electricity in the reactor by combining water input to the reactor (in an amount of 1 to 10 ppm of ethylene feed) and an electrostatic probe. This method has proven effective for Ziegler-Natta catalysts, but not for metallocene catalysts. U.S. Patent No. 6,548,610 discloses dome sheeting (or "drooling") by measuring the static charge using a Faraday drum and, if necessary, supplying a static control agent to the reactor to keep the measured charge within a predetermined range. How to prevent it is described.

When using a metallocene catalyst, various technologies have been developed to improve process stability. For example, various supporting procedures or methods for preparing metallocene catalyst systems with reduced fouling propensity and superior operability are discussed in U.S. Patent No. 5,283,278, which describes prepolymerization of metallocene catalysts. has been initiated. Other supporting methods are described in U.S. Patent Nos. 5,332,706, 5,473,028, 5,427,991, 5,643,847, 5,492,975, 5,661,095 and PCT Publications WO 97/06186, WO 97/15602 and WO 97/27224. has been initiated. Other literature has discussed various modifications to improve reactor continuity using metallocene catalysts and conventional Ziegler-Natta catalysts. See PCT Publication Nos. WO 96/08520, WO 97/14721 and US Pat. Nos. 5,627,243, 5,461,123, 5,066,736, 5,610,244, 5,126,414 and EP 0549252. A variety of other methods exist for improving operability, including coating the polymerization equipment, controlling the rate of polymerization, especially at start-up, and altering the reactor design and injecting various agents into the reactor.

In connection with the injection of various agents into the reactor, antistatic agents (antistatic agents) and process “continuous additives” have been the subject of various publications. For example, EP 0453116 discloses the introduction of antistatic agents into the reactor to reduce the amount of sheets and agglomerates. U.S. Patent No. 4,012,574 discloses adding a surface-active compound having a perfluorocarbon group to a reactor to reduce fouling. WO 97/46599 discloses that the catalyst feed stream may contain an antifouling or antistatic agent such as Atmer 163 (available from ICI Specialty Chemicals, Baltimore, MD). Although many references, including the above patents, mention antistatic agents, in most cases static electricity is never completely removed. Rather, it reduces it to an acceptable level by generating a charge opposite to that present in the polymerization system. In this regard, these "antistatic" agents are actually "pro-static" agents that create a compensating charge that reduces the net static charge in the reactor.

As described in US Patent Application Publication No. 2008/027185, aluminum stearate, aluminum distearate, ethoxylated amines, Octastat 2000, polysulfone copolymers with polyamines and mixtures of oil soluble sulfonic acids (Statsafe, ), as well as mixtures of carboxylated metal salts and amine-containing compounds, such as those sold under the trade names Kemamine and Atmer, can be used to control the level of static electricity in the reactor.

The static control agents described above can result in reduced catalyst productivity. Reduced productivity may exist as a result of residual moisture in the additive. Also, the reduced productivity may be due to interactions of the polymerization catalyst with the static control agent, such as reaction or complexation with hydroxyl groups in the static control agent compound. Depending on the static control agent used and the amount of static control agent needed to inhibit sitting, a loss of catalytic activity of 40% or more was observed.

In accordance with the foregoing, there is a need for additives useful for controlling the level of static electricity in the reactor and thus the seating, especially when metallocene catalyst systems are applied to fluidized bed reactors.

Accordingly, an object of the present invention is to provide an olefin polymerization method using an antistatic agent for a metallocene olefin polymerization process including diglycerol oleate.

Another object of the present invention is to provide an antistatic agent for a metallocene olefin polymerization process, in which discontinuity events are effectively reduced and continuous operation is possible for a long time, and the final product obtained can be applied to various applications including food contact applications. It is to provide an olefin polymerization method using

In order to achieve the above object, the present invention is a step of forming a mixture in which an antistatic agent containing diglycerol oleate is mixed with a low molecular hydrocarbon, the antistatic agent mixture, a metallocene catalyst, and aluminoxane. A process for olefin polymerization comprising feeding a metallocene-based catalyst composition to two or more polymerization reactors and polymerizing one or more alpha-olefins in the presence of the antistatic agent mixture and the catalyst composition.

In the olefin polymerization method using the antistatic agent for the metallocene olefin polymerization process according to the present invention, diglycerol oleate is used as an antistatic agent, so that discontinuity events are effectively reduced and continuous operation for a long time is possible. , the resulting final product can make polyolefin polymers that can be applied in a variety of applications including food contact applications.

1 is a view showing an olefin polymerization method according to an embodiment of the present invention.
2 is a diagram showing the result of the temperature profile inside the fluidized bed reactor according to an embodiment of the present invention.
Figure 3 is a view showing the results of the amount of antistatic agent and catalyst productivity according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail. In the following description, the polyolefin resin is simply referred to as a polymer or polyolefin, or referred to as an ethylene-based polymer, a polymer, a polymer, an olefin polymer, or the like, as necessary.

The olefin polymerization method using the antistatic agent for the metallocene olefin polymerization process according to the present invention comprises the steps of forming a mixture in which an antistatic agent containing diglycerol oleate is mixed with a low molecular hydrocarbon, the antistatic agent mixture and the metal feeding a metallocene-based catalyst composition comprising a rosene catalyst and an aluminoxane to two or more polymerization reactors and polymerizing one or more alpha-olefins in the presence of the antistatic mixture and catalyst composition. .

The antistatic agent serves to effectively remove static electricity generated during the polymerization process of olefins such as ethylene or propylene. can be lowered below a level that can cause a discontinuity event due to the phenomenon of the polymer layer formation on the walls of the reactor can be prevented, eliminated or reduced.

The antistatic agent is a liquid antistatic agent, and includes diglycerol oleate, which is a component extracted from palm oil. When used in polymerization processes, it can be useful as an antistatic agent. Since diglycerol oleate used as the antistatic agent is a component extracted from palm oil, products made using the antistatic agent can be safely used for food contact applications.

By forming a mixture in which diglycerol oleate used as an antistatic agent according to the present invention is mixed with a low molecular hydrocarbon, the antistatic agent of the mixture is introduced into a polymerization reactor system and used in an olefin polymerization process. The low molecular hydrocarbon is a hydrocarbon having 6 to 40 carbon atoms, preferably a saturated hydrocarbon having 6 to 36 carbon atoms, and is specifically selected from the group consisting of hexane, heptane, toluene, mineral oil, and mixtures thereof, more specifically hexane and use it In the mixture of diglycerol oleate and low molecular hydrocarbon, the concentration of diglycerol oleate is preferably 0.1 to 100% by weight, specifically 0.1 to 50% by weight, more specifically 0.5 to 10% by weight, based on the total mixture. do.

Two or more polymerization reactors for the polymerization of polyolefin polymers according to the present invention are suitable for homopolymerization of ethylene and copolymerization with any alpha-olefin comonomer, in particular by means of a solution, slurry or gas phase polymerization apparatus, a slurry or Polymerization mechanisms used in gas phase polymerization processes are suitable. More specifically, the one or more polymerization reactor systems preferably use a polymerization process in which one or more reactors selected from the group consisting of a gas phase reactor, a slurry reactor, and a solution reactor are connected in series, specifically a loop reactor for pre-polymerization; A polymerization reactor in which one or more prepolymerization reactors selected from the group consisting of a CSTR reactor for prepolymerization and a fluidized bed reactor and one or more fluidized bed reactors are connected in series may be used.

The polymerization reaction conditions according to each polymerization reactor system are the type of metallocene catalyst component, the composition of the supported catalyst, the type of monomer and comonomer, the polymerization method (eg, solution polymerization, slurry polymerization, gas phase polymerization, etc.), obtaining It may be variously modified according to the desired polymerization result or the shape of the polymer. For example, in such an olefin polymerization reaction, the olefin polymerization process may be performed at a polymerization reaction temperature of about 20 to 200 °C and a polymerization pressure of 10 to 7,000 psig.

The density of the olefin polymer prepared using the antistatic agent according to the present invention can be adjusted by changing the polymerization temperature or changing the comonomer concentration in the reactor. The molecular weight of the polyolefin of the present invention can be controlled by changing the polymerization temperature or changing the hydrogen concentration in the reactor.

polymerization method

In the olefin polymerization method according to the present invention, the antistatic agent mixture in which the low molecular hydrocarbon and diglycerol oleate are mixed is continuously supplied to the catalyst composition and the polymerization reactor. 1 is a view showing an olefin polymerization method according to the present invention by way of example, and specifically, the antistatic agent mixture (1, 4, 7) and the catalyst composition (1 ') are each independently two or more polymerization reactors (2, 5), the polymerization reactor system may include a solution, gas phase, slurry phase and high pressure process or a combination thereof, specifically, in an exemplary embodiment of the present invention, the olefinic monomers ethylene and alpha- Gas phase polymerization of 1-hexene, an olefin comonomer, is provided. The polymerization reactor is a prepolymerization loop reactor (2) for prepolymerizing ethylene and one or more alpha-olefins in the presence of a metallocene-based catalyst composition (1′) and an antistatic agent mixture (1) and polymerizing the prepolymer It includes a configuration in which fluidized bed reactors 5 for forming olefin polymers are connected in series. In the polymerization reactor, an olefin polymer may be formed by a conventional polymerization process (pre-polymerization and/or main polymerization process). For example, the metallocene catalyst composition (1′) and the antistatic agent mixture (1) are introduced into the prepolymerization loop reactor (2), where ethylene and alpha olefin may be added alone or mixed, and the molecular weight regulator Hydrogen may be added together to form a prepolymer under certain reaction conditions. The prepolymer may be introduced into a fluidized bed reactor (5) to form an olefin polymer (8) under certain reaction conditions. The polymerization process system of the present invention is suitable for use in any prepolymerization and/or polymerization process over a wide range of temperatures and pressures. The polymerization temperature in the prepolymerization reactor may range from -60 °C to about 280 °C, preferably from 0 °C to about 150 °C, in more specific embodiments from 30 °C to 100 °C, and in yet other embodiments from 30 °C to 60 °C. can The polymerization temperature in the fluidized bed reactor may range from -60 °C to about 280 °C, preferably from 50 °C to about 200 °C, in more specific embodiments from 60 °C to 120 °C, and in yet another embodiment from 60 °C to 90 °C. can

The antistatic agent mixture may be supplied to the polymerization reactor independently or together with the metallocene catalyst composition. Specifically, when the antistatic agent mixture and the metallocene catalyst composition are supplied independently, the antistatic agent mixture and the catalyst composition are continuously injected into the polymerization reactor through independent feeding lines, respectively, to the polymerization reactor, It may be introduced at one or more locations selected from the group consisting of a front end of the reactor, a rear end of the reactor, an inside of the reactor, and a recycle line.

When the antistatic agent mixture and the catalyst composition are supplied together, it is the same that the antistatic agent mixture and the catalyst composition are continuously injected through independent feeding lines, but before the two independent lines reach the polymerization reactor system, the polymerization reactor or put into a polymerization reactor after being combined with each other in a line connected to; or stirring the antistatic agent mixture and the catalyst composition in a separate stirrable container for a predetermined time, and then supplying the mixture to the polymerization reactor through a line connected to the reactor.

The polymerization process of the present invention further includes continuously injecting a liquid antistatic agent before polymerization, during polymerization, and after polymerization in order to remove static electricity generated in the reactor. The injection location of the antistatic agent may include a front/back end of the reactor, a reactor, and a catalyst storage tank. Specifically, the antistatic agent is supplied to the prepolymerization loop reactor 2, the fluidized bed reactor 5, and the line 4 connecting the prepolymerization loop reactor and the fluidized bed reactor, respectively. At this time, it is preferable that the antistatic agent is an antistatic agent mixture mixed with a low molecular hydrocarbon. When the antistatic agent is used alone without mixing with a low molecular hydrocarbon, the amount of the antistatic agent is used in a relatively small amount, for example, in a ppm level, compared to the polymer to be produced, so it is difficult to inject a metered amount. However, due to the high viscosity of the antistatic agent itself, a separate input facility such as a high-viscosity transfer pump is required, which can complicate the process.

When it is determined that the material flow inside the reactor due to static electricity is not smooth by monitoring the internal temperature, pressure, and density profile of the polymerization reactor, the level of static electricity is lowered by increasing the amount of the antistatic agent introduced. When an appropriate amount of antistatic agent is added, the material flow inside the reactor becomes smooth again. Since the level of static electricity generated varies depending on the type of catalyst used, process conditions, and the molecular weight, molecular weight distribution, and density of the polymer produced, the amount of antistatic agent added must be appropriately adjusted according to the level of static electricity generated. Preferably, the total concentration of the antistatic agent is preferably 1 to 2,000 ppmw (parts per million weight), specifically 2 to 1,000 ppmw, more specifically 2 to 200 ppmw, and more specifically 50 to 60 ppmw in the polymer product. do. If the concentration of the diglycerol oleate is less than 1 ppmw, there is a problem in that static electricity removal performance and catalyst productivity (mileage, mileage, weight of polymer formed per unit catalyst weight) are lowered, and if it exceeds 2,000 ppmw, catalyst productivity is greatly reduced. there is a problem. The term ppmw means parts per million weight, and for example, 2,000 ppmw means that diglycerol oleate is included as much as 0.2 wt% of the polymer product present in the reactor.

In addition, in the one or more polymerization reactors, the flow rate of diglycerol oleate may be different, for example, according to an embodiment of the present invention, the flow rate of diglycerol oleate in the loop reactor for pre-polymerization is 10 to 100 g/h, preferably 50 g/h, and the flow rate of diglycerol oleate in the fluidized bed reactor is 5 to 50 g/h, preferably 20 g/h, and the loop reactor and fluidized bed for prepolymerization are The flow rate of diglycerol oleate in the line connecting the reactor is 5 to 50 g/h, preferably 20 g/h.

In addition, catalyst productivity (mileage) is the weight of the polymer formed per unit catalyst weight, and the mileage (catalyst productivity) is 1,000 g/g or more, preferably 1,400 g/g or more, based on the input amount of diglycerol oleate. .

The olefin polymer according to the present invention is obtained by polymerizing one or more alpha-olefins, and is preferably a copolymer of ethylene, an olefinic monomer, and an alpha-olefin comonomer. As the comonomer, an alpha-olefin having 3 or more carbon atoms may be used. The comonomer having 3 or more carbon atoms is, for example, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, and 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene or 1-eicosene. The content of the alpha-olefin comonomer may be 1 to 4 mol%, preferably 1.4 to 4 mol%, based on 100 mol% of the ethylene and alpha-olefin copolymer, but is not limited thereto. If the content of the alpha-olefin comonomer is less than 1 mol%, there is a problem of reduced productivity due to a decrease in the activity of the catalyst system, and if it is more than 4 mol%, the melting point of the resin is low, causing sheeting in the reactor during gas phase polymerization. can

The weight average molecular weight (Mw) of the olefin polymer prepared according to the present invention may be 50,000 to 200,000 g/mol, preferably 60,000 to 170,000 g/mol, and more preferably 100,000 to 160,000 g/mol, but is limited thereto It is not. If the weight average molecular weight (Mw) of the polyolefin resin is less than 50,000, there is a problem of low physical properties and generation of fumes during extrusion processing, and if it exceeds 200,000, there is a problem of lowering extrusion processing efficiency (high energy consumption per extrusion amount) there is.

The polyolefin resin according to the present invention is composed of a copolymer of ethylene and an alpha-olefin comonomer, and the melt index (MI2.16, 190 ° C., 2.16 kg load condition) of the polyolefin resin is 0.01 to 15 g / 10 min, specifically 0.03 to 10 g/10 min, and the density is 0.88 to 0.98 g/cm 3 , specifically 0.90 to 0.96 g/cm 3 .

The metallocene-based catalyst composition according to the present invention may include a supported metallocene catalyst, specifically a metallocene catalyst and an aluminoxane, and more specifically a metallocene catalyst, an aluminoxane and a porous carrier. can include

The metallocene catalyst component may include one or more metallocene compounds, and specifically, various metallocene components commonly used in ethylene polymerization may be used without limitation, but a metallocene represented by the following formula (1) It is preferred to use a compound.

In Formula 1, Cp is a cyclopentadienyl radical, and R1 and R2 are each independently hydrogen, phosphine, amino, alkyl having 1 to 20 carbon atoms, alkoxy, alkylamino, dialkylamino, alkoxy-alkyl, carbon atoms 2 to 20 alkenyl, 6 to 20 carbon atoms, aryl, aryloxy-alkyl, alkylaryl, or arylalkyl radicals, such as methyl, 1-propyl, 1-butyl, methoxy, etc., preferably 1 - One or more types of propyl or 1-butyl are included. M is a Group 4 transition metal of the periodic table, that is, titanium, zirconium, and hafnium, and X is each independently halogen (eg, chloride (Cl), etc.), C1-C20 alkyl, alkoxy, C2-C20 alkenyl, aryl of 6 to 20 carbon atoms, alkylaryl, arylalkyl or aryloxy radicals, such as chloride, methyl, benzyl and the like.

The aluminoxane serves as an activator or cocatalyst, and generally includes methylaluminoxane (MAO) or modified methylaluminoxane (MMAO; Modified MAO) known to be suitable for olefin polymerization, as well as any commercially available aluminoxane. Aluminoxanes can also be used. The aluminoxane can be prepared by adding an appropriate amount of water to trialkyl aluminum or by reacting trialkyl aluminum with a hydrocarbon or inorganic hydrate salt containing water. It has the form of green acid. A typical linear aluminoxane is represented by the compound represented by the following formula (2), and a typical circular aluminoxane is represented by the compound represented by the following formula (3).

In Formulas 2 and 3, R' is a hydrocarbon radical, preferably a linear or branched alkyl radical having 1 to 10 carbon atoms. In Formulas 2 and 3, most of R' is preferably a methyl group, more preferably 30 to 100%, and most preferably 50 to 70% of the repeating unit is a methyl group. In Formula 2, x is an integer of 1 to 50, preferably 4 to 30, and y in Formula 3 is an integer of 3 to 50, preferably 4 to 30.

The aluminoxane is commercially available in the form of various types of hydrocarbon solutions. Among them, it is preferable to use an aromatic hydrocarbon solution aluminoxane, and it is more preferable to use aluminoxane dissolved in toluene.

As the porous carrier, porous particles having a stable structure, such as inorganic oxides or inorganic salts, may be used without limitation. Practically useful carriers are inorganic oxides of elements belonging to groups 2, 3, 4, 5, 13 or 14 of the periodic table, such carriers include silica, alumina, silica-alumina, or mixtures thereof, clays or modified It is preferable to use modified clay or a mixture thereof, and it is more preferable to use silica having spherical particles. Water or a hydroxyl group (—OH) must be removed from the inorganic oxide carrier before use, which can be performed through heat treatment. The heat treatment of the porous carrier is carried out by heating at a temperature of 200 to 800 ° C. while fluidizing the carrier in a vacuum or nitrogen atmosphere. The porous carrier is used in the form of a dried powder, has an average particle size of about 1 to 250 μm, preferably 10 to 150 μm, and a surface area of about 5 to 1,200 m / g, preferably about 50 to 500 m / g. is g. The pore volume of the porous carrier is 0.1 to 5 cm 3 /g, preferably 0.1 to 3.5 cm 3 /g, and the pore size is about 5 to 50 nm, preferably 7.5 to 35 nm. It is preferable that about 0 to 3 mmol of a hydroxy group (-OH) is present per 1 g of silica on the surface of the porous carrier, and more preferably, 0.5 to 2.5 mmol of a hydroxy group (-OH) is present, and such a hydroxy group The amount of (-OH) depends on the dehydration or calcination temperature of the carrier.

The supported catalyst may be prepared by various methods, and in one of them, the metallocene catalyst component and the activator are dissolved in a solvent, reacted for a certain time, and then a porous carrier is added to react under specific conditions. After that, the supported catalyst is completed through washing and drying processes.

Interruption due to sheeting or drooling in the olefin polymerization process by forming an olefin polymer using the antistatic agent containing diglycerol oleate and the metallocene catalyst composition according to the present invention together (Discontinuity Event) is effectively reduced, enabling long-term continuous operation, and the obtained final product can be applied to various applications including food contact applications.

Hereinafter, the present invention will be described in more detail through examples, but the following examples are intended to illustrate the present invention, and the present invention is not limited by the following examples.

Antistatic agents and catalysts used in the comparative examples and examples are as follows.

Statsafe 6000 : contains polysulfone, polyamine, sulfonic acid, Castor Oil and heptane and is available from Innospec.

Antistatic agent according to the present invention : diglycerol oleate

Zirconium-based metallocene supported catalyst : Bis (1-butyl-3-methylcyclopentadienyl) zirconium dichloride (manufactured by s-PCI, Korea) as a catalyst component, 20% by weight MAO toluene solution (Albemarle) as a cocatalyst ) and silica (product name: ES70X, manufactured by PQ) as a carrier, and a supported metallocene catalyst in solid form.

The polymerization reactions described in Comparative Polymerization Example 1, Polymerization Examples 1 and 2, and Polymerization Experimental Examples 1 and 2 are carried out in a continuous pilot-scale gas phase fluidized bed reactor (a loop reactor for pre-polymerization is connected in series in front of the fluidized bed reactor). , wherein the fluidized bed was composed of polymer particles. Gaseous feed streams of ethylene and hydrogen along with 1-hexene as liquid comonomer were introduced into the loop reactor for prepolymerization and the recycle gas lines of the gas phase fluidized bed reactor, respectively. The composition inside the reactor was kept constant by controlling individual flow rates of ethylene, hydrogen, and 1-hexene. The ethylene concentration was controlled to maintain a constant ethylene partial pressure. The hydrogen was controlled to maintain a constant hydrogen to ethylene mole ratio. The 1-hexene was controlled to maintain a constant 1-hexene to (ethylene+1-hexene) molar ratio. A relatively constant gas composition was ensured in the recycle gas stream by measuring the concentration of each gas in the reactor using an on-line gas chromatograph. The supported zirconium-based metallocene catalyst was introduced into a loop reactor for pre-polymerization using propane after soaking in propane. The amount of catalyst injected was adjusted to maintain a constant production rate.

The reaction bed of growing polymer particles was maintained in a fluidized state by continuous flow of make-up feed and propane gas through the reaction zone. This was achieved using apparent gas velocities of 0.7 to 0.9 m/s. The reactor pressure was maintained at 20 kg/cm 2 and the reaction temperature was maintained at 73°C. The fluidized bed was maintained at a constant height by withdrawing a portion of the bed at a rate equal to the rate of formation of the particulate product. The product formation rate (polymer production rate) ranged from 10 to 20 kg/h. The product was removed semi-continuously through a series of valves into a fixed volume chamber. This product was purged to remove entrained hydrocarbons and treated with a small amount of humidified nitrogen steam to inactivate any traces of residual catalyst.

After diluting the liquid antistatic agent with hexane (5 or 13% by weight), a loop reactor for pre-polymerization; fluid bed reactor; And it was injected into the line connecting the loop reactor and the fluidized bed reactor, and when it was determined that the material flow inside the reactor due to static electricity was not smooth by monitoring the temperature, pressure, and density profile inside the reactor during polymerization, the amount of the antistatic agent injected By changing the static electricity level (Level) was lowered. When an appropriate amount of antistatic agent was added, it was confirmed that the material flow inside the reactor became smooth again. At the three antistatic agent injection points, the flow rate of the antistatic agent was independently controlled. According to the results of the monitoring, if the injection flow rate of the antistatic agent is independently adjusted at the three antistatic agent injection points, the static electricity level can be lowered more efficiently and the material flow can be made smooth. Polymerization methods and experimental results according to specific comparative examples and examples are as follows.

[Polymerization Comparative Example 1] Preparation of polyolefin polymer (using Statsafe 6000)

Tests were performed in the above polymerization reactor system, Statsafe 6000 was used as an antistatic agent, and process stability thereof was evaluated. Using the zirconium-based metallocene supported catalyst described above, a reaction temperature of 73 ° C., a reaction pressure of 20 kg / cm 2, 1-hexene to (ethylene + 1-hexene) molar ratio of 1: 0.02 to 0.025, hydrogen to ethylene molar ratio Furnace 1: The reactor was carried out under conditions of 0.0002 to 0.00025, and polyethylene having a melt index of 0.90 g / 10 min (MI2.16, 190 ° C., 2.16 kg load conditions) and a density of 0.9164 g / cm 3 was produced. A liquid antistatic agent diluted with hexane (Statsafe 6000) was used, and a loop reactor for pre-polymerization; fluid bed reactor; and a line connecting the loop reactor and the fluidized bed reactor. At the beginning of the polymerization reaction, Statsafe 6000 diluted with hexane (13% by weight) was added to the loop reactor for pre-polymerization; fluid bed reactor; and a line connecting the loop reactor and the fluidized bed reactor; 50 g/h, 20 g/h, and 20 g/h, respectively. For the resulting polymer, the antistatic agent concentration averaged 165 ppmw.

[Polymerization Example 1] Preparation of Polyolefin Polymer (Antistatic Agent Input Amount Experiment)

In order to determine the input amount of the antistatic agent according to the present invention, diglycerol oleate diluted with hexane (5% by weight) was put into a loop reactor for pre-polymerization; fluid bed reactor; and a line connecting the loop reactor and the fluidized bed reactor; Polymerization was carried out in the same manner as in Comparative Polymerization Example 1, except that 50 g/h, 20 g/h, and 20 g/h were added to each, and the molar ratio of 1-hexene to (ethylene + 1-hexene) was 1:44, hydrogen The reaction was carried out under conditions of 1:4,450 to ethylene molar ratio. Under the same polymerization reactor system and polymerization conditions as in Comparative Polymerization Example 1, reactor fouling, catalyst productivity (mileage, mileage, weight of polymer formed per unit catalyst weight), and polymer characteristics according to the change in the input amount of diglycerol oleate (Melt index (MI2.16), density) were compared, and the results are shown in Table 1 below.

diglycerol oleate, ppmw
(Compared to Total Feed) Melt index (MI2.16), g/10min Density, g/cm Mileage
(catalyst productivity),
g-PE/g-Cat fouling 0 0.89 0.9178 730 error 2 0.94 0.9172 1,371 Good 51 0.93 0.9157 1,498 Good 60 0.97 0.9164 1,473 Good 162 0.75 0.9158 1,379 Good 970 0.79 0.9153 1,162 Good 1,600 0.84 0.9166 864 Good

Referring to Table 1, in the case of mileage (catalyst productivity), a relatively high mileage (catalyst productivity) of 1,400 g/g or more was shown at a specific input amount of diglycerol oleate (51 to 60 ppmw, compared to Total Feed), When diglycerol oleate was not added or an excess amount (1,600 ppmw) was added, a low mileage (catalyst productivity) of 1,000 g/g or less was exhibited.

In the case of fouling of the inner wall of the reactor, it was good when the input amount of diglycerol oleate was 2 ppmw or more. Based on this result, the input amount of diglycerol oleate according to the present invention may be 2 to 1,000 ppmw, preferably 50 to 60 ppmw. When the input amount was 1,600 ppmw or more, it was disadvantageous in terms of mileage (catalyst productivity), and when it was less than 2 ppmw, it was disadvantageous in terms of both mileage (catalyst productivity) and fouling. Therefore, in Polymerization Example 2 and Polymerization Experimental Examples 1 and 2 below, diglycerol oleate was added at a concentration of 50 to 120 ppmw compared to Total Feed.

[Polymerization Example 2] Preparation of polyolefin polymer (using antistatic agent: diglycerol oleate)

Following Polymerization Comparative Example 1, diglycerol oleate diluted with hexane (5% by weight) in an online T/C (Online Type-Change) method was used in a loop reactor for pre-polymerization, a fluidized bed reactor, and connecting the loop reactor and the fluidized bed reactor. Polymerization was performed in the same manner as in Comparative Polymerization Example 1, except that 50 g/h, 20 g/h, and 20 g/h were added to the lines, respectively. The antistatic agent concentration in the resulting polymer averaged 55 ppmw for the polymer product.

[Polymerization Experimental Example 1] Preparation of polyolefin polymer (antistatic agent: using diglycerol oleate/Statsafe 6000 mixture (1:1, w/w))

In order to confirm the mixing effect of heterogeneous liquid antistatic agents, diglycerol oleate according to the present invention and Statsafe 6000 were mixed in a weight ratio of 1: 1, and then the liquid antistatic agent diluted with hexane (5% by weight) was mixed with Polymerization Example 2, Polymerization Comparative Example 1 and Polymerization was performed in the same manner. The antistatic agent concentration in the polymer averaged 61 ppmw for the polymer product.

[Polymerization Experimental Example 2] Preparation of polyolefin polymer (antistatic agent: diglycerol oleate extension experiment)

In order to confirm the effect of increasing the injection amount of diglycerol oleate after performing on-line T/C again from the 1:1 mixed antistatic agent diluted solution performed in Polymerization Experimental Example 1 to the diglycerol oleate diluted solution according to the present invention, the fluidized bed Polymerization was carried out in the same manner as in Comparative Polymerization Example 1, except that the flow rate introduced into the reactor was increased from 20 g/h to 100 g/h. The antistatic agent concentration in the resulting polymer averaged 120 ppmw for the polymer product.

[Experimental Example 1] Polymer analysis result

The melt index and density of the polymers formed in the experiments conducted in Polymerization Comparative Example 1, Polymerization Example 2, and Polymerization Experimental Examples 1 and 2 were measured and are shown in Table 2 below.

division Melt index (MI2.16), g/10min Density, g/cm Polymerization Comparative Example 1 0.90 0.9164 Polymerization Example 2 0.92 0.9161 Polymerization Example 1 0.98 0.9169 Polymerization Example 2 0.74 0.9148

Referring to Table 2, by controlling the individual flow rates of ethylene, hydrogen, and comonomer, the polymers formed during the 7-day experiment conducted by Comparative Polymerization Example 1, Polymerization Example 2, and Polymerization Experimental Examples 1 to 2 had similar melting properties. It can be seen that it has an exponent and a density.

[Experimental Example 2] Fluidized bed reactor internal temperature profile result

Figure 2 shows the temperature profile inside the fluidized bed reactor collected during the tests conducted by the polymerization comparative examples and polymerization examples. As shown in FIG. 2, no discontinuity event occurred during the 7-day test conducted by Polymerization Comparative Example 1, Polymerization Example 2, and Polymerization Experimental Examples 1 and 2. Compared to Polymerization Comparative Example 1 (using Statsafe 6000), it can be seen that the temperature fluctuation range is narrow in Polymerization Example 2 and Polymerization Experimental Examples 1 to 2 (diglycerol oleate used as an antistatic agent). Compared to Statsafe 6000, it can be seen that the reduction in temperature fluctuation due to the use of an antistatic agent (diglycerol oleate) according to the present invention resulted from the formation of a more stable fluidized bed through more efficient static electricity control.

[Experimental Example 3] Antistatic agent input amount and catalyst productivity result

Figure 3 shows the input amount (concentration, ppmw) of the antistatic agent and the resulting catalyst productivity (Mileage, weight of polymer formed per unit catalyst weight). As confirmed in FIG. 3, the antistatic agent (diglycerol oleate) according to the present invention provided excellent process stability even at a lower concentration of the antistatic agent compared to Statsafe 6000. It can be seen that the catalyst productivity was improved by more than 20% compared to the present invention.

Claims (13)

Forming an antistatic agent mixture in which an antistatic agent containing diglycerol oleate is mixed with a low molecular weight hydrocarbon, which is a saturated hydrocarbon having 6 to 40 carbon atoms;
supplying a metallocene-based catalyst composition comprising the antistatic agent mixture and a metallocene catalyst and an aluminoxane to two or more polymerization reactors; and
polymerizing one or more alpha-olefins in the presence of the antistatic agent mixture and the catalyst composition;
The polymerization reactor includes a prepolymerization loop reactor for prepolymerizing ethylene and one or more alpha-olefins in the presence of an antistatic agent mixture and a metallocene-based catalyst composition, and prepolymerization of ethylene and one or more alpha-olefins in a loop reactor. A fluidized bed reactor for polymerizing a polymerized prepolymer to form an olefin polymer is connected in series,
supplying an antistatic agent mixture to the prepolymerization loop reactor, the fluidized bed reactor, and a line connecting the prepolymerization loop reactor and the fluidized bed reactor;
The concentration of diglycerol oleate in the mixture of the antistatic agent and the low molecular hydrocarbon is 0.1 to 50% by weight, olefin polymerization method. The method of claim 1, wherein the low molecular hydrocarbon is selected from the group consisting of hexane, heptane, toluene, mineral oil, and mixtures thereof. delete delete delete The method of claim 1, wherein the concentration of the antistatic agent is 1 to 2,000 ppmw in the polymer product. delete The method of claim 1, wherein the antistatic agent mixture is supplied to the polymerization reactor independently of the catalyst composition, or supplied in a mixed form. The method of claim 8, wherein the antistatic agent mixture and the catalyst composition are independently supplied, the antistatic agent mixture and the catalyst composition are continuously injected through independent feeding lines, respectively, to one or more polymerization reactors, the reactor The olefin polymerization method, which is supplied from one or more input positions selected from the group consisting of the front end, the rear end of the reactor, the inside of the reactor, and the recycle line. The method of claim 8, wherein the antistatic agent mixture and the catalyst composition are supplied in a mixed form, the antistatic agent mixture and the catalyst composition are continuously injected through independent feeding lines, and after being combined with each other in a line connected to the polymerization reactor, the polymerization reactor Which is put into, an olefin polymerization method. 11. The method of claim 10, wherein the antistatic agent mixture and the catalyst composition are supplied in a mixed form, after stirring the antistatic agent mixture and the catalyst composition in a separate container for a certain time, they are supplied to the polymerization reactor through a line connected to the polymerization reactor. Which will be, olefin polymerization method. 2. The method of claim 1, wherein the alpha-olefin is selected from ethylene; and propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-Hexadecene, 1-octadecene and 1-eicosene, which will include at least one member selected from the group consisting of, an olefin polymerization method. The method of claim 1, wherein the melt index (MI2.16, 190 ℃, 2.16 kg load condition) of the polymerized olefin polymer is 0.01 to 15 g / 10min, and the density is 0.88 to 0.98 g / cm 3, olefin polymerization method.

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